Disc flutter compensating suspension

ABSTRACT

A suspension is provided, which has proximal and distal ends and a longitudinal axis extending from the proximal end toward the distal end. A rotating hinge rotates the distal end about the longitudinal axis in response to vertical motion of the distal end relative to the proximal end. In one example, the suspension includes a preformed twist deformation, which rotates the distal end about the longitudinal axis relative to the proximal end axis in a direction opposite to rotation by the rotating hinge, in response to the vertical motion.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of and claims priority from U.S.application Ser. No. 11/284,200, filed Nov. 21, 2005, the content ofwhich is hereby incorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

The present invention relates generally to suspensions such as thoseused in data storage devices, and more particularly but not bylimitation to a suspension having a vertically offset hinge structure.

BACKGROUND

Suspensions are used in a variety of different fields for preciselypositioning one element relative to another element, wherein one of theelements may be moving relative to the other element. For example, datastorage systems use suspensions for positioning transducers relative tostorage media.

One type of data storage system is known as a “disc drive”, which usesone or more rigid or flexible discs coated with a magnetizable mediumfor storing information in a plurality of circular, concentric datatracks. The discs are mounted on a spindle motor, which causes the discsto spin and the surfaces of the discs to pass under respectivehydrodynamic (e.g., air) bearing disc head sliders. The sliders carrytransducers, which write information to and read information from thedisc surface. An actuator mechanism moves the sliders from track totrack across the surfaces of the discs under control of electroniccircuitry. The actuator mechanism includes a track assessing arm, asuspension and a gimbal for each slider, for example. The suspensionincludes a load beam, which provides a load force that forces the slidertoward the disc surface. The gimbal is positioned between the slider andthe load beam, or is integrated in the load beam, to provide a resilientconnection that allows the slider to pitch and roll while following thetopography of the disc.

As track densities continue to increase, it becomes more difficult forthe suspension and control circuitry to position the transduceraccurately over a desired data track. As a result, storage capacity maybe limited. One factor limiting this precision is relative motionbetween the transducer and the disc caused by disc flutter. Disc flutteris characterized by axial motion of the disc due to dynamic excitationfrom the driving motor, support bearings, and aerodynamic forces withinthe drive. These excitations set up resonances within the discplatter(s) which have strong axial/vertical displacement components.This vertical response causes a radial displacement of the concentricdata tracks. This radial motion can therefore cause misregistrationbetween the transducer relative to the track during track followingoperations. U.S. Pat. Nos. 5,999,369 and 6,088,192 discuss some of thesevibrational modes and some attempts to reduce track misregistration.

Embodiments of the present invention provide solutions to these andother problems, and offer other advantages over the prior art. However,embodiments of the present invention are not limited by or required toprovide these or other solutions or advantages.

SUMMARY

One embodiment of the present invention is directed to a suspensionhaving a base, a load beam and a multiple layer hinge structure. Thehinge structure and at least one of the base and the load beam areformed of a single contiguous piece of multiple layer laminate materialcomprising first and second layers. The hinge structure comprises afirst beam formed by the first layer and a second beam formed by thesecond layer. The first layer is absent along the second beam, and thesecond layer is absent along the first beam such that the first andsecond beams are vertically offset from one another. The first andsecond beams extend between the base and the load beam.

Another embodiment of the present invention is directed to a devicecomprising a proximal section and a distal section, wherein at least oneof the proximal and distal sections have a recessed portion and alaterally-offset non-recessed portion. The device further comprises ahinge structure adjacent the recessed and non-recessed portions. Thehinge structure comprises first and second laterally offset beamsextending between the proximal and distal sections and having top andbottom surfaces. The first beam is attached to the non-recessed portion,and the second beam is attached to the recessed portion such that thetop and bottom surfaces of the first beam are vertically offset from thetop and bottom surfaces, respectively, of the second beam in a directionnormal to the surfaces.

Another embodiment of the present invention is directed to a suspension,which comprises proximal and distal ends and a longitudinal axisextending from the proximal end toward the distal end. A rotating hingebetween the proximal and distal ends rotates the distal end about thelongitudinal axis in response to vertical motion of the distal endrelative to the proximal end. The suspension further comprises apreformed twist deformation, which is confined to an area on thesuspension that is entirely distal to the rotating hinge and whichtwists the distal end about the longitudinal axis relative to theproximal end in a direction opposite to rotation by the rotating hinge.

Other features and benefits that characterize embodiments of the presentinvention will be apparent upon reading the following detaileddescription and review of the associated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a data storage device in which someembodiments of the present invention are useful.

FIG. 2A is a perspective view of the back side of a suspension withinthe data storage device shown in FIG. 1, according to one embodiment ofthe present invention.

FIG. 2B is a perspective view of the suspension, as viewed from the discsurface.

FIG. 2C is an enlarged, fragmentary view of the suspension shown inFIGS. 2A and 2B.

FIG. 3A is a perspective view of the back side of a suspension accordingto an alternative embodiment of the present invention.

FIG. 3B is a perspective view of the suspension shown in FIG. 3A, asviewed from the disc surface.

FIG. 3C is an enlarged, fragmentary view of the suspension shown inFIGS. 3A and 3B.

FIG. 4 is a perspective view of the back side of a suspension accordingto another alternative embodiment of the present invention.

FIG. 5 is a perspective view of the back side of a suspension accordingto another alternative embodiment of the present invention.

FIG. 6 is a perspective view of the back side of a suspension accordingto another alternative embodiment of the present invention.

FIG. 7 is a perspective view of a suspension according to anotheralternative embodiment of the present invention.

FIG. 8 is a graph, which illustrates a frequency response function ofseveral suspensions due to horizontal base plate excitation.

FIG. 9A is a perspective view of a disc flutter compensating suspensionhaving a localized twist in the load beam according to one embodiment ofthe present invention.

FIG. 9B is an exploded view of the suspension shown in FIG. 9A.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1 is a perspective view of a data storage device 100 in which someembodiments of the present invention are useful. In this example, datastorage device 100 is a disc drive. However, embodiments of the presentinvention can be used in other types of data storage devices and inother non-storage applications, such as those applications in which asuspension can be used to position one element relative to another.

In the embodiment shown in FIG. 1, data storage device 100 includes ahousing with a base 102 and a top cover (not shown). Data storage device100 further includes a disc pack 106, which is mounted on a spindle 109by a disc clamp 108. Disc clamp 108 includes a plurality of individualdiscs, which are co-rotated about spindle 109 by a spindle motor (notshown) attached to the bottom of the spindle 109. Each disc surface hasan associated disc head slider 110, which is mounted to data storagedevice 100 for communication with the disc surface. As the disc pack isrotated, it generates air circulation through the disc drive and inparticular generates a fluid (e.g., air) bearing between each headslider 110 and each disc surface. The bearing surface of each slider canbe designed for non-contact, pseudo-contact or direct-contact with thedisc surface, for example.

In the example shown in FIG. 1, sliders 110 are supported by suspensions112, which are in turn supported by track accessing arms (or “actuatorarms”) 114. Track accessing arms 112 are radially positioned by afirst-stage actuator 116. Actuator 116 is of the type known as arotating moving coil actuator and includes a voice coil motor (VCM),shown generally at 118. Voice coil motor 118 rotates actuator 116 withits attached sliders 110 about a pivot shaft 120 to position sliders 110over a desired data track along a path 122 between a disc inner diameter124 and a disc outer diameter 126. Voice coil motor 118 operates undercontrol of servo control circuitry 130. Other types of first-stageactuators can also be used, such as linear actuators.

In addition, disc drive 100 can employ second stage actuators, commonlyreferred to as microactuators, for example, (not shown) which can belocated anywhere along the track accessing arms, suspension, gimbal orslider.

A. Vertical Offset

FIG. 2A is a perspective view of the back side of one of the suspensions112, according to one embodiment of the present invention. Suspension112 includes a proximal end 200, a distal end 201, a proximal section202, a hinge structure 203, a distal section 204 and a preload transfersection 205. Suspension 112 further includes a longitudinal axis 206.

In the example shown in FIG. 2A, proximal section 202 includes a basemounting portion 207, and distal section 204 includes a load beam 208.Base mounting portion 207 is attached to a base plate 210 such as bywelding, for example. Base plate 210 has a swage stake hub 212, which isused to mount base plate 210 and suspension 112 to a respective actuatorarm 114 shown in FIG. 1. Other methods of mounting can also be used.

Hinge structure 203 extends between base portion 207 and load beam 208and has an aperture 214, which defines a pair of laterally-spaced,flexible beams 216 and 218 that extend from base portion 207 to loadbeam 208. In one embodiment, beams 216 and 218 are formed with a preloadbend (not shown) about an axis transverse to longitudinal axis 206. Whensuspension 112 is assembled in disc drive 100 (shown in FIG. 1), thepreload bend supplies a preload force to slider 110 (also shown in FIG.1), which forces slider 110 toward the surface of the disc along avertical, Z-axis 217. Beams 216 and 218 lie in different planes that arevertically offset from one another along Z-axis 217 so that verticalmotion of the slider caused by disc flutter (or other vibrational modes,for example) creates an off-track motion along X-axis 219 due to arotating hinge action provided by hinge structure 203. As the disc movesup and down, a synchronous lateral motion with the moving disc arises,hence minimizing relative motion between the read-write head and thedata track. Arrow 220 shows an example of rotation at the distal end 201caused by upward vertical movement of the slider and the rotating hingeaction. Arrow 220 would be reversed for downward vertical motion.

Load beam 208 extends from hinge structure 203 to preload transfersection 205. Load beam 208 has a substantially planar main body portion222 and a pair of opposing lateral side edges 223 and 224. Load beam 208transfers the preload force generated by beams 216 and 218 to preloadtransfer section 205. In one embodiment, side edges 223 and 224 includea pair of respective stiffening rails (not shown), which are bentout-of-plane with respect to the main body portion 222 to provideadditional stiffness to the load beam section. However, load beam 208can be formed with or without stiffening rails in alternativeembodiments of the present invention.

Preload transfer section 205 extends generally from the distal end ofload beam 208 to the distal end 201 of suspension 112. Preload transfersection 205 has a load point 230 at which the load beam transfers thepreload force to the back surface of slider 110 (shown in FIG. 1). Aflexure or gimbal 232 is attached between load beam 208 and slider 110(or is alternatively integral with the load beam) to allow the slider topitch and roll while following the topography of the disc.

A flex circuit 240 is routed along and is supported by suspension 112for carrying electrical conductors that communicate with the read andwrite transducers carried by the slider.

In addition, the various elements of suspension 112 include one or morealignment holes or apertures, which are used for alignment purposes whenattaching the various elements together. In addition, the alignmentholes can provide access points for welding purposes.

FIG. 2B is a perspective view of suspension 112, as viewed from the discsurface. FIG. 2C is an enlarged, fragmentary view of suspension 112 asviewed from the same direction as FIG. 2B. FIG. 2B illustrates flexcircuit 240 routed along suspension 112 from proximal end 200 to distalend 201. In this embodiment, flex circuit 240 includes a top cover coat242, a circuit layer 243, comprising signal traces and insulatingdielectric material, and a bottom stainless steel layer 244. Stainlesssteel layer 244 can be welded or otherwise attached to the bottomsurfaces of suspension 112.

Referring to FIG. 2C, base portion 207, hinge structure 203 and loadbeam 208 have a multiple layer construction with a bottom layer 260, atop layer 262 and an intermediate core layer 264, which are laminatedtogether. In one embodiment, the top and bottom layers 260 and 262 areformed of thin sheets of metal, such as stainless steel, while corelayer 264 is formed of a non-metal, such as polyimide. These layers canbe connected together by a suitable method, such as with a pressuresensitive or other adhesive, for example. However, any other suitablematerials can be used in alternative embodiments. Also, each layer canhave any suitable thickness. For example in one embodiment, the top andbottom layers 260 and 262 have a thickness of 0.001 inches and corelayer 264 has a thickness of 0.003 inches.

FIG. 2C also illustrates a vertical offset 270 between beams 216 and 218in greater detail. In this embodiment, the material of bottom layer 260and core layer 264 is absent along substantially the entire length ofbeam 216, leaving only the material of top layer 262 of the multi-layersuspension 112. In contrast, the material of top layer 262 and corelayer 264 is absent along substantially the entire length of beam 218,leaving only the material of bottom layer 260. As a result, beam 216lies in a different plane than beam 218 since beam 216 is formed by thetop material layer and beam 218 is formed by the bottom material layer.

In an alternative embodiment, the core material 264 can remain on one orboth of the beams 216 and 218 while still maintaining the verticaloffset 270. The vertical offset 270 can be achieved with little or noincremental cost addition in substantially all existing laminatedsuspension designs. Existing laminated suspensions can simply be etchedor otherwise processed along beams 612 and 218 to remove the desiredmaterial layers and thereby obtain the vertical offset. Alternatively,beams 216 and 218 (and any of the other elements of suspension 112) canbe formed by an additive process instead of a material removal process.

In the embodiment shown in FIGS. 2A-2C, base portion 207, load beam 208and hinge structure 203 are contiguous, in which bottom layer 260 andtop layer 262 extend continuously through base portion 207, hingestructure 203 and load beam 208. However, one or more of these sectionscan be formed as separate pieces of material that are attached to oneanother in alternative embodiments of the present invention.

Referring back to FIG. 2B, top layer 262 is attached to base plate 210along base portion 207. Base portion 207 has an aperture 250, which isaligned with swage stake hub 212 (shown in FIG. 2A). The various layersof base portion 207 are staggered in order to expose top layer 262 sothat it can be welded or otherwise attached to base plate 210 (shown inFIG. 1A).

FIG. 3A-3C are perspective views of a suspension 300 in which the baseportion 207 and the hinge structure 203 are formed as a separate pieceof laminate material, which is attached to load beam 302, according toan alternative embodiment of the present invention. The same referencenumerals are used in FIGS. 3A-3C as were used in FIGS. 2A-2C for thesame or similar elements. FIG. 3A illustrates suspension 300 as viewedfrom the backside of the suspension relative to the disc surface. FIG.3B illustrates suspension 300 as viewed from the disc surface.

Suspension 300 includes a load beam 302 and a contiguous hinge-basesection 304. In this embodiment, load beam 302 is formed of a singlelayer of stainless steel and includes a pair of stiffening rails 306 and307, which are bent out-of-plane with respect to the main body portionof load beam 302. However, load beam 306 can have a multiple layerconstruction and can be formed with or without stiffening rails inalternative embodiments of the present invention. Load beam 302 has adistal end, which supports slider 110.

Hinge-base section 304 has multiple layers, including a bottom layer260, a top layer 262 and a core layer 264, similar to the embodimentshown in FIGS. 2A-2C. The distal end 310 of hinge-base section 304 isattached to the proximal end of load bean 302. The proximal end ofhinge-base section 304 is attached to base plate 210. In this example,top 262 is welded to the bottom surface of load beam 302 and to thebottom surface of base plate 210. Other attachment methods andarrangements can also be used.

Similar to the embodiment shown in FIGS. 2A-2C, layers 260, 262 and 264are selectively removed, such as by etching or another process, so thatbeams 216 and 218 are vertically offset from one another and lie indifferent planes. In this example, bottom layer 260 and core layer 264are removed along beam 216 such that beam 216 is formed only of toplayer 262. Top layer 262 and core layer 264 are removed along beam 218such that beam 218 is formed of only bottom layer 264. Again, core layer264 can be left remaining on one or both the beams 216 and 218 inalternative embodiments.

FIG. 3C is an enlarged, fragmentary view of suspension 300 illustratingthe hinge-base section 302 in greater detail. Bottom layer 260 and corelayer 264 are removed from the area of beam 216, and top layer 262 andcore layer 264 are removed from the area of beam 218 to provide thevertical offset between the two beams. In addition, hinge-base section304 includes a channel 320 for receiving flex circuit 240 such that theflex circuit is recessed within hinge-base section 304. In this example,channel 320 is formed by removing bottom layer 260 and core layer 264along the path of channel 320. This creates a partially enclosed channelthat extends from the side edge of the base portion to the center of theproximal end of load beam 302. Flex circuit 240 can be attached to toplayer 262 within channel 320. Recessing flex circuit 240 withinhinge-base section 304 protects the flex circuit from windage caused bythe rotating discs during operation. However, flex circuit 240 cansimply be attached to the surface of bottom layer 260 in an alternativeembodiment of the present invention.

In a further embodiment, hinge structure 203 is formed as a separateelement from base portion 207. For example, hinge structure 203 can beseparated from base portion 207 along dashed lines 350. In thisembodiment, the top layer 262 of hinge structure 203 would be attachedto the opposing surface of base plate 210, and the top surface 262 ofbase portion 207 would be attached to the opposing surface of base plate210. In another alternative embodiment, hinge 10 structure 203 could beattached to base portion 207.

FIG. 4 is a perspective view of the backside of a suspension 400according to another alternative embodiment of the present invention.Again, the same reference numerals are used in FIG. 4 as were used inthe previous figures for the same or similar elements. Suspension 400includes a proximal section 402, a distal section 404 and a hingestructure 406 therebetween. Proximal section 402 includes base plate210, and distal section 404 includes load beam 208. Load beam 208 caninclude a single or multiple-layer construction, with or withoutstiffening rails. Hinge structure 406 includes beams 216 and 218, whichare laterally and vertically offset from one another. Beams 216 and 218are formed of separate pieces of material, such as single-layer sheetsof stainless steel. However, beams 216 and 218 can be formed of othersingle or multiple-layer materials. Beam 216 is attached to the topsurface of base plate 210 and to the top surface of load beam 208,whereas beam 218 is attached to the bottom surface of base plate 210 andthe bottom surface load beam 208. Attachment to opposite surfaces ofbase plate 210 and/or opposite surfaces of load beam 208 verticallyoffsets the two beams from one another in a direction normal to the beamsurfaces.

In an alternative embodiment, one end of beams 216 and 218 are attachedto the same surface of load beam 218 and the other end of beams 216 and218 are attached to opposite surfaces of base plate 210. In anotheralternative embodiment, one end of beams 216 and 218 are attached toopposite surfaces of load beam 208 and the other end of beams 216 an 218are attached to the same surface of base plate 210. Also, the materialthat forms beams 216 and 218 can be expanded to cover larger portions orthe entire surface of base plate 210. Also, one or both of the beams 216and 218 can be formed out of the top or bottom layer of a multiple-layerload beam in an alternative embodiment of the present invention.Additional variations can also be made within the present invention.

FIG. 5 is a perspective view of a suspension 500 according to anotheralternative embodiment of the present invention. The same referencenumerals are used in FIG. 5 as were used in the previous figures for thesame or similar elements. Suspension 500 includes a proximal section502, a distal section 504 and a hinge structure 506. In this embodiment,beams 216 and 218 are formed of separate pieces of material, such assheets of stainless steel. The material forming beam 216 is contiguouswith the material forming base portion 207, which extends over and isattached to base plate 210. Base plate 210 includes a recessed portion510 and a non-recessed portion 512 that are adjacent to hinge structure506. Beam 216 is attached to non-recessed portion 512, and beam 218 isattached to recessed portion 510. Similarly, the proximal end of theback surface of load beam 208 includes a non-recessed portion 514 and arecessed portion 516 that are adjacent to hinge structure 506. Beam 216is attached to non-recessed portion 514, and beam 218 is attached torecessed portion 516.

Recessed portions 510 and 516 can be formed by any method such aspartial etching or stamping. In one embodiment, base plate 210 and loadbeam 208 have the same thickness, and recessed portions 510 and 516 havethe same depth relative to the non-recessed portions 512 and 514.However, recessed portions 510 and 516 can have different depths inalternative embodiments.

In a further embodiment, base plate 210 includes a further recessedportion on the bottom surface of the base plate, directly opposite torecessed portion 510 and which is a mirror image of recessed portion510. Placing a similar recesses on opposing surfaces of base plate 210allows for improved flatness control, especially for stamping processes.

FIG. 6 is a perspective view of a suspension 600 during an intermediatestage of manufacture, according to one embodiment of the presentinvention. Suspension 600 is similar to suspension 500 shown in FIG. 5,and the same reference numerals are used in FIG. 6 as were used in FIG.5 for the same or similar elements. In this embodiment, load beam 208and base plate 210 are initially formed as a single, contiguous piece ofmaterial with struts 602 and 604. Recessed portions 510 and 516 areetched from the material at the same time such that the partial etchingresults in the same step depth in both base plate 210 and load beam 208.Base plate 210 and load beam 208 can then be separated from one anotherby removing struts 602 and 604 later in the assembly process.

FIG. 7 is a perspective view of a suspension 700 according to anotheralternative embodiment of the present invention. The same referencenumerals are used in FIG. 7 as were used in the previous figures for thesame or similar elements. Suspension 700 includes a proximal section702, a distal section 704 and a hinge structure 706. In this embodiment,beams 216 and 218 are formed with base portion 207 as a single,continuous piece of material, such as a sheet of stainless steel. Thematerial forming base portion 207 extends over and is attached to baseplate 210. Base plate 210 includes a recessed portion 710 and anon-recessed portion 712 that are adjacent to hinge structure 706. Beam216 is attached to recessed portion 710, and beam 218 is attached tonon-recessed portion 712. Base portion 207 includes one or more struts714, which connect the material of base portion 207 that is attached torecessed portion 710 with the material of base portion 207 that isattached to non-recessed portion 712. Base portion 207 and beams 216 and218 can therefore be fabricated as a single, continuous piece ofmaterial with no additional alignment. During assembly, struts 714 arebent downward to allow the proximal end of beam 216 to be fixed torecessed portion 710.

Similar to the embodiment shown in FIGS. 3A-3C, distal section 704includes a load beam 302 formed of a single layer of stainless steel andincluding a pair of stiffening rails 306 and 307, which are bentout-of-plane with respect to the main body portion of load beam 302.However, load beam 306 can have a multiple layer construction and can beformed with or without stiffening rails in alternative embodiments ofthe present invention. Beam 216 is attached to one surface of load beam302, and beam 218 is attached to an opposite surface of load beam 302due to the offset provided by recessed portion 710.

With this embodiment, the recess in the base plate is sufficient tocreate the vertical offset between the preload beams 216 ad 218. Thesize of the gap (g) is a direct function of the depth (d) of the recessin base plate 210 and the thickness (t) of the hinge material, whereing=d−t. In order to maintain the offset or gap (g) on the load beam side,the preload beams 216 and 218 are welded, for example, to opposite sidesof load beam 302. If the load beam thickness is “g”, the preload beams216 and 216 will be parallel to one another.

This embodiment reduces variation in the part performance due to theload beam thickness and flatness having much less tolerance compared tothe tolerance of the depth and flatness of a recess formed in the loadbeam, similar to the embodiment shown in FIG. 5.

In an alternative embodiment, the recessed structure is applied to loadbeam 302 instead of or in addition to base plate 210. A recess can beformed in load beam 302 adjacent hinge structure 706, wherein one of thebeams 216 and 218 are attached to the recessed portion and the other ofthe beams is attached to the non-recessed portion of the load beam. Theother ends of beams 216 and 218 can be attached to the same or oppositesurfaces of base plate 210. Similar struts 714 can be used to link therecessed and non-recessed ends of beams 216 and 218 on the load beamside, if desired.

B. Twist

Several embodiments have been described above, which modify thesuspension to enable the recording head to better follow the tracks on afluttering disc. For example, a relative z-height offset is added to thepreload bend beams. These suspensions can be referred to as Disc FlutterCompensating (DFC) suspensions.

Modeling of the frequency response functions (FRFs) and actual data haveshown that this vertical offset can lead to an increase in contributionof the second bending mode to the head off-track motion. The verticaloffset of the preload beams causes a rotation (arrow 220 in FIG. 2A)about the longitudinal suspension axis for a vertical displacement ofthe recording head. The rotation causes a synchronized motion of therecording head with the disc track, minimizing relative motion for discvibrational modes. However, this rotation can also cause an increase inthe off-track contribution due to the second bending mode.

FIG. 8 illustrates the frequency response function due to horizontalbase plate excitation. FIG. 8 is a graph, which plots gain in dB as afunction of frequency in Hz. Line 800 represents a baseline suspensionhaving no vertical offset between the preload beams, line 801 representsa DFC suspension having vertical offset between the preload beams, andline 802 represents a DFC suspension further including a localized twistas described in more detail below with respect to FIGS. 9A and 9B.Off-track motion due to the second bending mode is highlighted by area804. The DFC suspension has a relatively large second bending modecontribution, while the DFC suspension with localized twist has areduced second bending mode contribution.

By pre-forming a local twist in the load beam, distal to the preloadbeams and opposite to the direction rotation due to the vertical offsetbeams, it is possible to reduce off-track motion due to the secondbending mode while not sacrificing the off-track sensitivity of the headto vertical excitation. Localizing the twist maintains the ability tofollow the disc as a DFC suspension. The location of the twist and thetwist angle are knobs that can be adjusted to optimize the secondbending mode contribution to off-track head motion.

FIG. 9A is a perspective view of a DFC suspension 900 having a localizedtwist in the load beam according to one embodiment of the presentinvention. Suspension 900 is similar to suspension 700 shown in FIG. 7but has a shim (shown in FIG. 7B) between load beam 302 and beam 218instead of a recess in base plate 210. In addition, both beams 216 and218 are attached to the same side of load beam 302 instead of oppositesides. The shim vertically offsets beam 216 relative to beam 218.

Suspension 900 is attached to base plate 210 and carries a flexure 232at its distal end. Similar to the embodiments discussed above, thevertical offset between beams 216 and 218 creates an off-track motionalong X-axis 219 in response to vertical motion of the slider due to arotating hinge action provided by hinge structure 203. Beams 216 and 218can be vertically offset according to any of the embodiments discussedabove and/or by tilting the suspension relative to base plate 210. Arrow220 shows an example of rotation at the distal end 201 caused byvertical movement of the slider and the routing rotating hinge action.

In order to counteract and reduce the second bending mode contributionto off-track motion, load beam 302 further includes a localized,preformed twist 910 about its longitudinal axis 206. In one embodiment,longitudinal axis 206 extends through the center of the swage area andthe center of the dimple in flexure 232. Twist 910 is preformed bybending or deforming an area of load beam 302 such that distal end 201becomes rotated relative to a proximal end of the load beam in a staticstate, as shown by arrow 920. In one embodiment, twist 910 has a twistangle 922 of approximately 2-3 degrees about longitudinal axis 206.However, other twist angles outside of this range can be used inalternative embodiments of the present invention.

At second bending mode frequencies, twist 910 has the effect of rotatingdistal end 201 about longitudinal axis 206 in a direction opposite torotation 220 by the rotating hinge, in response to the vertical motionof the distal end.

FIG. 9B is an exploded view of the suspension 900 shown in FIG. 9A. Inthis embodiment, load beam 302 is formed of a single layer of stainlesssteel. However, load beam 306 can be formed of other materials and canhave a multiple layer construction, with or without stiffening rails inalternative embodiments of the present invention. Shim 934 is positionedbetween load beam 302 and preload beam 218 for vertically offsettingbeam 218 relative to beam 216. Shim 934 can also result in load beam 302being tilted relative to base plate 210 about the longitudinal axis ofsuspension 900. If load beam 302 is tilted, beams 216 and 218 can lie inthe same plane as one another or in different planes. Alternatively,shim 934 can be replaced with one or more of the features discussedabove for vertically offsetting beam 216 relative to beam 218.

The static deformation in load beam 302 that creates twist 910 isconfined to an area 930 that is entirely distal to hinge structure 203.In one embodiment, area 930 is confined between and not overlapping anarea 932 at the proximal end of the load beam, where preload beams 216and 218 are attached, and distal end 210 of load beam 302. In thisembodiment, the proximal area 932 and the distal end 201 are free of anypreformed material deformation that creates twist in these areas aboutlongitudinal axis 206. Twist 910 is localized to area 930. Thislocalization allows the twist to reduce off-track head motion due to thesecond bending mode while not sacrificing the off-track sensitivity ofthe head to vertical excitation.

It is to be understood that even though numerous characteristics andadvantages of various embodiments of the invention have been set forthin the foregoing description, together with details of the structure andfunction of various embodiments of the invention, this disclosure isillustrative only, and changes may be made in detail, especially inmatters of structure and arrangement of parts within the principles ofthe present invention to the full extent indicated by the broad generalmeaning of the terms in which the appended claims are expressed. Forexample, the particular elements may vary depending on the particularapplication for the suspension or device while maintaining substantiallythe same functionality without departing from the scope and spirit ofthe present invention. In addition, although the preferred embodimentdescribed herein is directed to a suspension for supporting a transducerin a data storage system, it will be appreciated by those skilled in theart that the teachings of the present invention can be applied tonon-storage applications in which suspensions are used to suspend andobject, without departing from the scope and spirit of the presentinvention.

1. A suspension comprising: proximal and distal ends; a longitudinalaxis extending from the proximal end toward the distal end; a rotatinghinge between the proximal and distal ends, which rotates the distal endabout the longitudinal axis in response to vertical motion of the distalend relative to the proximal end; and a preformed twist deformation,which rotates the distal end about the longitudinal axis relative to theproximal end axis in a direction opposite to rotation by the rotatinghinge, in response to the vertical motion.
 2. The suspension of claim 1wherein the rotating hinge is free of any twist deformation about thelongitudinal axis.
 3. The suspension of claim 1 wherein preformed twistdeformation is confined to an area between and not-overlapping therotating hinge and the distal end.
 4. The suspension of claim 1 wherein:the suspension comprises a proximal mounting section and a load beam;and the rotating hinge comprises first and second laterally offset beamsextending between the proximal mounting section and the load beam andcomprising top and bottom surfaces, wherein the top and bottom surfacesof the first beam are offset from the top and bottom surfaces,respectively, of the second beam in a direction normal to the surfaces.5. The suspension of claim 4 and further comprising: a shim positionedbetween the proximal mounting section and the load beam such that theshim offsets the top and bottom surfaces of the first beam from the topand bottom surfaces, respectively, of the second beam in a directionnormal to the surfaces.
 6. The suspension of claim 1 wherein: thesuspension comprises a base and a load beam; and the rotating hingestructure statically tilts the load beam relative to the base about thelongitudinal axis.
 7. The suspension of claim 1 wherein the preformedtwist deformation is confined to an area on the suspension that isentirely distal to the rotating hinge.
 8. A device comprising: a firstsection; a second section, at least one of the first and second sectionshaving a recessed portion and a laterally-offset non-recessed portion;and a hinge structure adjacent the recessed and non-recessed portionsand comprising first and second laterally offset beams extending betweenthe first and second sections and having top and bottom surfaces,wherein the first beam extends from the non-recessed portion and thesecond beam extends from the recessed portion such that the top andbottom surfaces of the first beam are vertically offset from the top andbottom surfaces, respectively, of the second beam in a direction normalto the surfaces.
 9. The device of claim 8 wherein: the first section hasfirst and second opposite surfaces, the first surface comprising therecessed portion and the non-recessed portion adjacent the hingestructure:
 10. The device of claim 9 wherein: the first beam is attachedto one surface of the second section and the second beam is attached toan opposite surface of the second section.
 11. The device of claim 9wherein the hinge structure comprises material that extends from thefirst and second beams and overlaps at least a portion of the firstsection and comprises at least one strut extending from the material onthe non-recessed portion to the material on the recessed portion. 12.The device of claim 9 wherein the first section further comprises afurther recessed portion on the second surface, opposite the recessedportion on the first surface.
 13. The device of claim 9 wherein thesecond section comprises a recessed portion and a non-recessed portionadjacent the hinge structure, and wherein the first beam is attached tothe non-recessed portion of the second section and the second beam isattached to the recessed portion of the second section.
 14. The deviceof claim 13 wherein the first section and the second section are formedof the same thickness of material and the recessed portions in the firstand second sections have the same step depth relative to thenon-recessed portions.
 15. The device of claim 8 wherein the first beamis attached to a first surface of the first section and the second beamis attached to a second, opposite surface of the first section.
 16. Thedevice of claim 8 wherein the device comprises a suspension, the firstsection comprises a base plate and the second section comprises a loadbeam.